1. Field of the Invention
This invention relates generally to the art of thin film device processing and fabrication. More specifically, the invention relates to the structure of Organic Light Emitting Diode devices and displays.
2. Related Art
In OLED (Organic Light Emitting Diode) technology there are four main approaches to generate white light for illumination: A single white stack (A), a vertical RGB stack (B), a horizontal RGB stack (C) and a blue stack combined with a phosphor (D). In FIG. 1, the advantages and disadvantages of these approaches are given. The spectral output of a single white stack (approach A) cannot be tuned very easily. The basic disadvantage of approach B is a lower efficiency due to electron trapping caused by the red organic emitter. Approach C is tunable and is expensive and difficult to manufacture. The shortcoming of approach D is the blue emitter, which usually offers lower quantum efficiency as well as reliability compared to a green emitter. Thus, there is a need for an efficient and tunable device structure to generate white light.